深空天线组阵相关合成算法的Simulink仿真与分析

为对深空网天线组阵中几种相关合成算法进行分析比较,构建了一种新的Simulink仿真模型。将其应用于某测控站天线组阵试验数据,验证了模型的可行性。在此仿真模型下,对Simple、Sumple和Matrix-free 算法进行了频标同源/频标不同源、弱信号/强信号、2/3/6个天线等组阵情况下的仿真分析。三种算法在频标同源情况下的合成效率均优于不同源的情况;强信号组阵情况下,三种算法的信噪比合成性能基本相当;Simple算法在6天线情况下,信噪比合成性能下降;Sumple算法在组阵的天线数目很少时,合成信噪比较低且不稳定,在天线数目较多时性能良好;Matrix-free算法性能稳健,合成效率始终大于95%。该Simulink仿真模型对于进行天线组阵信号相关算法的分析具有一定的价值。     

Forecasting China's foreign exchange reserves using dynamic model averaging: The roles of macroeconomic fundamentals,financial stress and economic uncertainty

We develop models for examining possible predictors of growth of China's foreign exchange reserves that embrace Chinese and global trade, financial and risk (uncertainty) factors. Specifically, by comparing with other alternative models, we show that the dynamic model averaging (DMA) and dynamic model selection (DMS) models outperform not only linear models (such as random walk, recursive OLS-AR(1) models, recursive OLS with all predictive variables models) but also the Bayesian model averaging (BMA) model for examining possible predictors of growth of those reserves. The DMS is the best overall across all forecast horizons. While some predictors matter more than others over the forecast horizons, there are few that stand the test of time. The US–China interest rate differential has a superior predictive power among the 13 predictors considered, followed by the nominal effective exchange rate and the interest rate spread for most of the forecast horizons. The relative predictive prowess of the oil and copper prices alternates, depending on the commodity cycles. Policy implications are also provided.     

郑州市城市农业发展现状与创新发展模式策略研究

[目的]城市农业与城市的经济、生态、社会、文化融为一体,是解决目前我国城市发展过程中面临的资源紧缺、劳动力问题、生态环境恶化和可持续发展等问题的有效途径之一,集生产、生活、生态、示范等多种功能于一体。郑州市人口众多,对城市农业的需求强烈,政府高度重视城市农业发展,将其确定为"十三五"规划发展的重点内容之一。[方法]文章通过现场调研、访谈调研和文献调研等形式,分析了郑州市中心城区各种城市农业类型的发展现状,在补充市民食物供给、改善市民生活环境、丰富市民生活和促进农业文化传承四方面的发展需求。[结果]计算了平面和立体上的城市农业发展空间,包括平面空间上的2.5万hm2耕地和58.35km2公共绿地,立体空间上的115万m2阳台农业发展空间、230万m2屋顶农业发展空间、2 300万m2墙体垂直农业发展空间。[结论]提出了"十三五"期间郑州市应大力推进阳台农业和农业主题公园模式,引导规范休闲农园、屋顶农业和庭院农业模式,适量引进垂直农业、社区农园、植物工厂和公共绿化农业模式的建议,为促进郑州市城市农业发展提供决策参考。     

Robust Markowitz mean‐variance portfolio selection under ambiguous covariance matrix

This paper studies a robust continuous‐time Markowitz portfolio selection problem where the model uncertainty affects the covariance matrix of multiple risky assets. This problem is formulated into a min–max mean‐variance problem over a set of nondominated probability measures that is solved by a McKean–Vlasov dynamic programming approach, which allows us to characterize the solution in terms of a Bellman–Isaacs equation in the Wasserstein space of probability measures. We provide explicit solutions for the optimal robust portfolio strategies and illustrate our results in the case of uncertain volatilities and ambiguous correlation between two risky assets. We then derive the robust efficient frontier in closed form, and obtain a lower bound for the Sharpe ratio of any robust efficient portfolio strategy. Finally, we compare the performance of Sharpe ratios for a robust investor and for an investor with a misspecified model.     

Prioritization of government expenditure on health in India: A fiscal space perspective

Unequal distribution of fiscal resources and lower prioritization of budget towards healthcare are the most important challenges in achieving universal health coverage in India. This study has examined relationships between government health expenditure and fiscal space (i.e. tax revenue, non-tax revenue, fiscal transfer, and borrowings) in twenty-one states of India for the period of 1980–2014. Our panel regression results imply that mobilization of tax revenue has a positive impact, while borrowings have a negative impact on the allocation of government expenditure on healthcare in the long-run. The panel quantile regression results show that states associated with the low and middle level of revenue growth have been mobilizing finance through central government transfer and borrowings in short-run. Further, the panel vector error correction models show that sum of the lagged coefficients of borrowings have a greater impact on health financing process as compared to other sources of fiscal space at short-run, and the speed of adjustment towards long-run equilibrium is relatively slower. The overall analysis concludes that less domestic revenue mobilization and higher dependency of borrowings for healthcare financing may create fiscal stress on state finances in the long-run, and thereby it could possibly reduce the prioritization of spending. Therefore, improvement in revenue growth and proper utilization of fiscal transfer would be appropriate policy implications from this study.     

政府质量、科技创新与绿色GDP——中国省际空间溢出效应及区域差异对比

通过构建嵌入政府质量和科技创新因素的经济增长模型，利用中国30个省份2004~2017年的平衡面板数据，实证检验政府质量、科技创新对绿色GDP发展的影响。研究发现：中国绿色GDP存在显著的空间集聚性及明显的区域差异性。在经济权重矩阵影响下，不同地区的政府效率、市场化程度、公平程度和腐败程度对绿色GDP的影响不同，其中政府效率、公平程度能有效促进经济发展较好地区的绿色GDP增长，却会抑制比较落后地区绿色GDP的增长；市场化程度对大部分地区绿色GDP呈现促进作用；腐败程度对地区绿色GDP增长呈阻碍作用。科技创新对各地区绿色GDP均起到积极的促进作用。因此，提升绿色GDP发展水平不仅需要提高地方政府质量，为绿色GDP发展提供符合实际的政策指导意见，还需激活企业科技创新能力，为绿色GDP发展提供有力科技保障。     

黄浦江两岸地区公共空间可达性研究 ——基于社会网络分析的公共交通评价与 优化策略

黄浦江两岸地区正在打造世界级的滨江公共空间， 如何便捷、多样地抵达滨江公共空间是其规划设计和建设实施 的重要评价指标。将该评价指标定义为滨江公共空间可达性， 指居民利用滨江公共交通系统(常规公交)抵达滨江公共空间的 便捷性和多样性程度。利用社会网络分析方法，以虹口区和徐 汇区的滨江公共空间为例，构建了滨江公共空间可达性模型， 借助地理信息系统(ArcGIS)与计算机编程语言(Python)对现 状可达性进行量化分析评价，并提出优化滨江公共空间可达性 的算法和策略，以期更好地提升滨江公共空间可达性。     

基于多源数据的国土空间高质量利用评价思路

研究目的：新时代国土空间规划背景下，提出利用多源数据评价国土空间高质量利用的思路，为辅助编制高质量的国土空间规划提供支撑。研究方法：文献分析法、归纳演绎法。研究结果：在国土空间规划新趋势下，以国土空间高质量利用内涵为引导，提出生态空间、农业空间和城镇空间的高质量利用目标与评价维度，并构建了基于多源数据的国土空间高质量利用的评价方法框架。研究结论：国土空间高质量利用评价应在统筹各类空间不同目标间关系的基础上，结合研究和实践需要，因地制宜进行评价，进而形成各空间的发展合力，推进国土空间的高质量利用。     

建成环境如何影响老年人绿地使用频率 ——基于可达性和吸引力双重视角

老年人绿地使用频率与其体力活动水平和健康生活质量密切相关，且严重依赖绿地自身及周边建成环境。针对既有研究多集中于可达性分析的局限性，从可达性和吸引力双重视角出发，结合大连市老年人绿地活动调查数据，深入探究建成环境与老年人绿地使用频率的统计学关联性。研究发现：与空间临近性相比，绿地实际可达性对老年人活动的影响更为显著；不同绿地类型影响老年人的使用频率，社区公园和游园是高频体力活动的重要场所；此外，高品质的绿地环境、与居住用地相混合、临近生活性街道，以及周边多样化网点布局，均可正向调节老年人绿地使用频率。为营造老年友好型绿地，从空间配置、场所塑造、路径可达和功能诱发4个方面，提出结构化的建成环境优化策略。     

The first space hotel employees: Human resources challenges in a post-terrestrial paradigm

ABSTRACT

This article discusses some of the issues regarding the first employees to work in a space hotel. As space hotels initially will be vastly different to existing hotels on Earth, it is important to question what human resource challenges this will raise for hospitality workers and providers. To assist reflection on this issue, the notions of space tourism and space tourist are explored, and a definition of a space hotel is included to create product and service boundaries. Plausible futures methodology is used to create five main human resource considerations and concludes by suggesting this sector is largely unexplored.